Much drier Canadian air will take up residence across the region over the next day or two, giving a crisp quality to the sunny weather and mild temperatures. In fact, in the lower Hudson Valley, temperatures are expected to fall all the way to the upper 40s late Wednesday night. That’s sweater weather, folks.

It won’t be quite so chilly in New York City, as warm concrete and closer proximity to the ocean will help moderate what would otherwise be a chilly night. Temperatures in the five boroughs will bottom out in the low 60s as a result.

However, this cool down will be only a tease, as temperatures warm near 90 again as the remnants of Hurricane Isaac track their way northward over the coming few days.

As Hurricane Isaac begins to move inland along the Gulf Coast, rain showers will follow. For New Yorkers, this means the waiting game now begins for the storm’s torrential rains to inch toward the tri-state. Five day rainfall projections can’t see quite enough into the future yet to show Isaac’s impacts on New York City, but you can get a glimpse of the magnitude of the coming rains by checking out the half-foot totals awaiting parts of the drought-stricken Ohio Valley. Isaac arrives in Greater New York a shell of his former self (as happens with so many eager young New York residents), but the potential for some short-lived flooding is there.

Monday’s Greater New York forecast roundup:

WSJ Headquarters in Manhattan:

Actual High: 80; High feels like: 79

Actual Low: 64; Low feels like: 62

Weather: A brief stretch of fall begins

Brooklyn: 80/63

Queens: 81/67

Bronx: 81/63

Staten Island: 83/62

Poughkeepsie, N.Y.: 79/47

Trenton, N.J.: 87/61

Islip, Long Island: 86/63

New Haven, Conn.: 86/58

Meteorologist Eric Holthaus contributes daily weather reports and analysis on Metropolis. For the latest on conditions in New York and elsewhere, follow his updates (@WSJweather) on Twitter.